As shown in FIG. 1, conventional ethanol production systems (1) may mill whole corn (2) into a mixture of corn particles (3) (referred to hereinafter as “milled corn”) which may include particles of corn bran, corn endosperm and corn germ. The milled corn (3) can be transferred to the ethanol production process (4) which includes the conventional steps of fermentation, distillation, and dehydration to generate an amount of ethanol (5). In the fermentation step, the milled corn (3) may be combined with an amount of water and an amount of alpha-amylase (or other enzyme capable of liquefying corn starch) to generate a mash in which the starch of the corn endosperm is liquefied. The mash may be held for a period of time at a temperature of between about 120 degrees Celsius (° C.) and about 150° C. to kill bacteria in the mash. The mash may then be held at a temperature of between about 90° C. and about 100° C. for a duration of time sufficient to achieve a desired level of liquefication of the starch. An amount of gluco-amylase (or other enzyme capable of generating fermentable sugars from the liquefied starch) added to the mash converts the liquefied starch to fermentable sugars, such as dextrose, in a process referred to as saccharification. Yeast can then be added to the mash to convert the sugars to an amount of ethanol (5) and an amount of, carbon dioxide (6) (or CO2) along with other volatile organics. The amount of carbon dioxide (6) can be stored or sold in the marketplace. For sale in to certain markets or for certain applications, the amount of carbon dioxide (6) can be stripped of the other volatile organics and captured as an amount of purified carbon dioxide (9). The fermented mash often referred to as “beer” comprises an amount of ethanol (5) in a concentration of about eight percent to about twelve percent by weight, other liquids and non-fermentable solids. The amount of ethanol (5) in the beer can be separated and concentrated to about 190 proof by conventional distillation techniques and dehydrated by application to molecular sieve to produce a dehydrated ethanol of about 200 proof. The about 200 proof ethanol may be combined with up to about five percent denaturant to generate an amount of fuel grade ethanol (10).
The stillage which remains after distillation of the beer can comprise an amount of liquid typically referred to as “thin stillage” and an amount of remaining solids typically referred to as the “distillers grains”. The thin stillage can be separated from the distillers grains (for example by centrifugation). The distillers grains can be dried by evaporation of the remaining thin stillage. The thin stillage can be concentrated by evaporation of water to generate a syrup containing about thirty percent solids (also referred to as “condensed distiller soluble”). The syrup can be recombined with the dried distillers grains to generate an amount of distillers dried grain with solubles (7) (“DDGS”). The DDGS can be sold as animal feed (8).
The amount of thermal energy (11) (or energy Btus or Btus) utilized by the conventional ethanol production process (4), including the steps of fermentation, distillation and dehydration, and by-product handling, which results in about a gallon of fuel ethanol (5), and a corresponding amount of DDGS (7) and carbon dioxide (6) utilizes an amount of thermal energy (11) of between about 30,000 and 40,000 British thermal units (hereinafter “Btu”). This amount of thermal energy (11) is typically generated by burning a corresponding amount of fossil fuel (12) such as oil, coal oil, coal or natural gas. In certain particular ethanol production processes (4), an amount of the DDGS (7) may be burned to produce a part of this amount of thermal energy as described by United States Patent Application No. 2003/0019736A1.
Even though there is an increasing demand for fuel ethanol (10) worldwide and an increasing amount of research in ethanol production, there remain substantial unresolved problems with respect to conventional ethanol production.
A first substantial problem with conventional ethanol production process as above-described may be that it requires the use of fossil fuel(s) in whole or in part to generate the amount of thermal energy required for the ethanol production process. One aspect of this problem can be that the cost of fossil fuels, such as coal or natural gas, may increase in disproportion to the price of being paid for the ethanol produced. Additionally, there may be spot shortages of gas and coal due to availability whether due to production, purification, or conveyance to the ethanol production facility.
A second substantial problem with conventional ethanol production process as above-described can be that for each 1.0 Btu equivalent of fuel consumed in conventional ethanol production only about 1.4 Btu to about 2.0 Btu equivalents of fuel ethanol may be produced.
A third substantial problem with conventional ethanol production process can be that there may be no manner of substantially reducing the amount of thermal energy consumed in the ethanol production process.
A fourth substantial problem with conventional ethanol production process can be that there may be no manner of substantially increasing the amount of ethanol produced by ethanol production plant having a fixed construction form using conventional ethanol production processes.
A fifth substantial problem with conventional ethanol production process can be that there may be that the market for the DDGS or carbon dioxide produced as by-products of the ethanol production process may be too small to consume all the DDGS or carbon dioxide produced by the conventional ethanol production facility.